An Internet search of the term skin sensitization reveals its definition as:

“A condition that is ‘induced when a susceptible individual is exposed topically to (an) inducing chemical allergen. The chemical allergen provokes a cutaneous immune response which, if of the required magnitude and quality, will result in the development of contact sensitization’ and a subsequent exposure to the material will lead to allergic contact dermatitis (ACD).”

While it is relatively easy to find the definition of this term, it has been difficult to elucidate the cellular and molecular mechanisms by which the skin can become sensitized to certain materials, and even more difficult to develop in vitro tests to predict which materials have the potential to be sensitizing agents.

Since cosmetic and personal care product manufacturers have an obligation to ensure their products are not harmful to consumers, it is essential for them to test the skin sensitization potential of the ingredients used in their products. Presently, only animal-based methods are available for testing sensitization potential; however, the industry is emphasizing the need for animal-based method replacements. In response to this need, several interesting and promising approaches to in vitro skin sensitization testing are in development. Perhaps it will not be long before they are deemed valid and reliable alternatives to animal testing.